JPH11142355A - Conductivity measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductivity measuring apparatus in which is sample solution and a buffer solution do not stay, by which the conductivity of a fluid, to be measured, can be measured stably, whose accuracy can be enhanced and which can be miniaturized. SOLUTION: A conductivity measuring apparatus measures the conductivity of a fluid to be measured. The conductivity measuring apparatus is featured so as to be provided with a liquid flow passage 3 which is formed on a board 1, with at least two branch flow passage 4 which are formed in the downstream of the liquid flow passage 3 and with two conductivity measuring electrodes which are formed respectively inside the branch flow passages 4 from branch parts of the branch flow passages and which measure the conductivity of the fluid to be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductivity analyzer for a liquid analyzer for analyzing ions, such as an electrophoresis analyzer and an ion chromatograph analyzer. TECHNICAL FIELD The present invention relates to a conductivity measuring apparatus which can stably measure a sample liquid or a buffer liquid without stagnation, can improve accuracy, and can be reduced in size.

[0002]

2. Description of the Related Art FIG. 7 is an explanatory view of the configuration of a conventional example generally used in the prior art. For example, Japanese Patent Application No. 9-28818, filed by the applicant of the present invention, entitled "Conductivity Detection Type Electricity" 5, which was filed on Feb. 13, 1997.

In FIG. 7, reference numeral 1 denotes a glass substrate. 2
Is a cover glass that covers one surface of the glass substrate 1.

Reference numeral 3 denotes a liquid flow path formed by forming a groove in the glass substrate 1 and covering the groove with the cover glass 2. Reference numeral 4 denotes a branch flow channel provided on the glass substrate 1 so as to intersect the liquid flow channel 3 and used when the sample liquid B is injected.

[0005] Reference numeral 5 denotes two conductivity measurement electrodes, the tips of which are provided to face the glass substrate 1 and the tips of which are exposed to the liquid flow path 3. Reference numeral 6 denotes a buffer liquid tank connected to one end of the liquid flow path 3. Reference numeral 7 denotes a buffer waste liquid tank connected to the other end of the liquid flow path 3.

Reference numeral 8 denotes a buffer tank electrode provided in the buffer tank 6, to which a high voltage for electrophoresis is applied.
Reference numeral 9 denotes a buffer waste tank electrode provided in the buffer waste tank 7, to which a high voltage for electrophoresis is applied. 10 is
This is a separation channel having one end connected to the downstream end of the liquid channel 3. The separation channel 10 is a channel that separates the sample B for each component.

Reference numeral 11 denotes a sample liquid tank connected to one end of the branch flow channel 4. Reference numeral 12 denotes a sample waste liquid tank connected to the other end of the branch flow channel 4. 13 is a sample liquid tank 11
Is an electrode for a sample liquid tank provided in the above. Reference numeral 14 denotes a sample waste liquid tank electrode provided in the sample waste liquid tank 12. Note that platinum electrodes are used for the electrodes 8, 9, 13, and 14.

In the above configuration, a high voltage is applied between the buffer liquid tank electrode 8 and the buffer waste liquid tank electrode 9, and the liquid flow path 3 is filled with the buffer liquid A. Next, a sample liquid B is automatically introduced into the separation channel 10 by applying a voltage to the sample liquid tank electrode 13 and the sample waste liquid tank electrode 14.

Next, when a high voltage is applied between the electrode 8 and the electrode 9, the sample liquid B moves in the separation channel 10 while being separated according to the principle of electrophoresis. The conductivity is measured by the two conductivity measuring electrodes 5, and the component analysis of the sample liquid becomes possible.

FIG. 8 is an explanatory view of a manufacturing process of the substrate 1 in the embodiment of FIG. Here, (a) shows a front view and (b) shows a side view. Step 1 shows a groove forming step for the electric conductivity measuring electrode 5. An electrode groove 102 is formed in the glass substrate 101 by etching. In this case, the groove depth is 1 μm.

Step 2 shows a step of forming a groove in the liquid flow path 3. A channel groove 103 for an electrophoresis channel is formed in the glass substrate 101 by etching. In this case, 10μ
m groove depth.

Step 3 shows a step of forming the electric conductivity measuring electrode 5. A platinum electrode 104 is formed in the electrode groove 102 by sputtering in this case. The platinum electrode 104 has a thickness of 0.35 μm.

Step 4 is a step of bonding the cover glass 105 and filling the electrode groove 102 with a resin.
The cover glass 105 is bonded to the glass substrate 101. Resin 1 is inserted into the gap between cover glass 105 and platinum electrode 104.
Fill 06. In this case, an epoxy resin is used.

[0014]

In such an apparatus, an electrode groove 102 is required to join a cover glass 105 to a glass substrate 101.

However, in such an apparatus,
At the tip of the platinum electrode 104 exposed in the flow channel 103, the resin 106 cannot be completely filled, and the platinum electrode 10
For example, a dent of about 0.65 μm is formed at the tip of No. 4.

In this recess, buffer solution A and sample solution B
Solution tends to invade and stay.

Once the solution has been penetrated, it is difficult to replace the solution, which has caused disturbance of the chromatographic peak due to stagnation of the sample solution B and instability of the conductivity baseline. Therefore, the conductivity cannot be measured stably.

The present invention solves this problem. SUMMARY OF THE INVENTION An object of the present invention is to provide a conductivity measuring apparatus which can stably measure without a stagnation of a sample liquid or a buffer liquid, can improve accuracy, and can be reduced in size.

[0019]

According to the present invention, there is provided a conductivity measuring apparatus for measuring the conductivity of a measurement fluid, comprising: a liquid flow path provided in a substrate; At least two branch flow paths provided downstream of the flow path, and two conductivity measurement electrodes respectively provided from the branch portion of the branch flow path to the inside of the branch flow path to measure the conductivity of the measurement fluid A conductivity measuring device, comprising: (2) The conductivity measuring device according to (1), further including the liquid flow path, the branch flow path, and the two conductivity measurement electrodes formed by a semiconductor process. (3) The conductivity measuring device according to (1) or (2), further including a separation channel provided in the substrate and having one end connected to the liquid channel. (4) The conductivity measuring device according to (3), further comprising a substrate made of a glass material. (5) The conductivity measuring device according to (3), further comprising a substrate made of a polymer resin material. (6) The conductivity measuring device according to (1) or (2), further including a liquid flow path mostly constituted by a capillary tube. It is what constituted.

[0020]

In the above configuration, the sample injection power switch is turned on, and the unknown sample in the sample liquid tank is injected into the branch flow channel by electroosmotic flow. Turn off the power switch for sample injection and turn on the power switch for electrophoresis.

The ions are separated by the difference in the mobility of the ions of the sample, and pass through the conductivity measuring electrode in the order of ions having the highest mobility. Chromatography can be obtained by recording the change in conductivity when ions pass over the opposing conductivity measuring electrode. Hereinafter, a detailed description will be given based on embodiments.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of a main part of an embodiment of the present invention, FIG. 2 is a detailed view of a main part of FIG. 1, and FIG. 3 is a side sectional view of FIG. In the drawing, the same reference numerals as those in FIG. 7 indicate the same functions. Hereinafter, only differences from FIG. 7 will be described.

Reference numerals 21 and 22 denote at least two branch channels provided downstream of the liquid channel 3. 23 and 24 are
As shown in FIG. 2, from the branch portions of the branch flow paths 21 and 22,
Two conductivity measurement electrodes are provided in the branch flow paths 21 and 22 to measure the conductivity of the measurement fluid.

However, there are sufficient gaps in the branch flow paths 21 and 22 through which the measurement fluid passes. Reference numeral 25 denotes a first buffer waste liquid tank which communicates with the terminal end of the branch channel 21 and is provided on the cover glass 2.

Reference numeral 26 denotes a first buffer waste liquid tank electrode provided in the first buffer waste liquid tank 25. 27
Is a second buffer waste liquid tank provided in the cover glass 2 and communicating with the terminal end of the branch flow path 22.

Reference numeral 28 denotes a second buffer waste liquid tank electrode provided in the second buffer waste liquid tank 27. 29,
Reference numeral 31 denotes a high-voltage power supply for electrophoresis and a high-voltage power supply switch for electrophoresis provided between the buffer liquid electrode 8, the first buffer waste liquid electrode 26, and the second buffer waste liquid electrode 28. is there.

Reference numerals 32 and 33 denote a sample injection power supply and a sample injection power switch provided between the sample liquid tank electrode 13 and the sample waste liquid tank electrode 14, respectively. 3
Reference numeral 4 denotes a conductivity detector provided between the first buffer waste liquid tank electrode 26 and the second buffer waste liquid tank electrode 28. The conductivity detector 34 includes an AC constant voltage power supply 341 and a current detector 342.

In the above configuration, the sample injection power switch 33 is turned on, and the unknown sample B in the sample liquid tank 11 is injected into the separation channel 10 by electroosmotic flow. The sample injection power switch 33 is turned off, and the electrophoresis power switch 31 is turned on.

The conductivity measuring electrodes 23 and 23 are separated according to the difference in the mobility of the ions of the sample B in the order of ions having the highest mobility.
Pass over 24. Opposing conductivity measuring electrodes 23 and 24
Chromatographs can be collected by recording the change in conductivity as ions pass above.

The measurement of the electric conductivity is performed by an alternating current. in this case,
This is performed at a frequency of about 2 kHz. Conductivity measuring electrodes 23, 24
Of the electroosmotic flow flowing from the separation flow path 2 does not disturb even if it reaches the branch flow paths 21 and 22, and flows evenly when the DC potential of Therefore, the chromatographic peak is not disturbed.

However, in an analyzer such as an ion chromatograph which does not use an electroosmotic flow, it is not always necessary to make the DC potentials of the two conductivity measuring electrodes 23 and 24 coincide.

As a result, (1) Since the electrode groove 22 is not separately required as in the conventional example, there is no influence of the stagnation of the sample solution B or the buffer solution A, the measurement can be performed stably, and the accuracy can be improved. A conductivity measuring device is obtained.

(2) Since the fine liquid flow path 3 and the fine conductivity measuring electrodes 23 and 24 can be manufactured by utilizing the micro-machining technology, a miniaturized conductivity measuring device can be obtained.

(3) If the separation channel 10 is incorporated in the substrate 1, there is no need to provide the separation channel 10 separately.
An inexpensive conductivity measuring device can be obtained without requiring any man-hours for mounting the separation channel 10.

(4) If the separation channel 10 is incorporated in the substrate 1, an electrophoresis detection device that can be easily miniaturized as a whole is obtained.

(5) If a glass material is used for the substrate 1, the surface treatment is easy, as in the case of a commercially available glass capillary tube, and a measuring device optimal for the sample liquid to be detected can be obtained.

(6) If a polymer resin material is used for the substrate 1, a conductivity measuring device capable of easily performing chemical modification suitable for separation can be obtained.

FIG. 4 is an explanatory view of the manufacturing process of the example of FIG. Here, (a) shows a front view and (b) shows a side view.
Step 1 shows a groove forming step of the flow paths 3, 4, 10, 21, and 22. The channels 3, 4, 10, 21, and 22 are formed in the glass substrate 1 by etching. In this case, 5
The groove depth is set to μm.

Step 2 is to conduct the conductivity measuring electrodes 23 and 24
Is shown. In the flow paths 21 and 22 of the glass substrate 1,
In this case, a platinum electrode is formed by sputtering, and the conductivity measuring electrodes 23 and 24 have a thickness of 0.35 μm.

Step 3 shows a joining process of the cover glass 2. The cover glass 2 provided with holes corresponding to the buffer liquid tank 6, the sample liquid tank 11, the sample waste liquid tank 12, the first buffer waste liquid tank 25, and the second buffer waste liquid tank 27 in advance is bonded to the glass substrate 1. Then, a buffer liquid tank 6, a sample liquid tank 11, a sample waste liquid tank 12, a first buffer waste liquid tank 25, and a second buffer waste liquid tank 27 are formed.

FIG. 5 is an explanatory view of the structure of a main part of another embodiment of the present invention, and FIG. In this embodiment, FIG.
In the embodiment, the liquid flow path 3, the separation flow path 10, and the detector main body are configured as an integrated chip. However, only a part of the detector main body 41 and the separation flow path 10 are manufactured by a semiconductor process, and the liquid flow Instead of the passage 3 and most of the separation passage 10, a commercially available capillary tube 42 is used.

FIG. 5 shows a state where the cover glass 2 is removed for easy understanding. FIG.
Shows a state where the cover glass 2 is assembled. Since only the detector main body 41 and a part of the separation channel 10 need to be manufactured, an inexpensive electrophoresis detection device can be obtained. Further, when the resolution is deteriorated, the capillary tube 52 may be replaced, so that an electrophoresis detection device which can reduce the maintenance cost can be obtained.

[0043]

As described in detail above, according to the first aspect of the present invention, (1) unlike the conventional example, no separate electrode groove is required, so that the sample solution or the buffer solution is retained. A conductivity measuring device which can be measured stably without any influence and which can improve the accuracy can be obtained. (2) Since a fine liquid flow path and a fine conductivity measuring electrode can be manufactured using the micromachining technology, a miniaturized conductivity measuring device can be obtained.

According to the second aspect of the present invention, (1) Since a semiconductor process generally used can be used, an inexpensive, minute and highly accurate conductivity measuring apparatus can be obtained. (2) Since the semiconductor process can be precisely manufactured on the substrate, a high degree of assembly accuracy of the conductivity measuring electrode detector is not required, and since the substrate is in the form of a substrate, the substrate can be easily replaced and the inexpensive conductivity can be obtained. A rate measuring device is obtained.

According to the third aspect of the present invention, (1) since the separation channel is incorporated in the substrate, there is no need to separately provide the separation channel, and the number of steps for mounting the separation channel is also required. Thus, an inexpensive conductivity measuring device can be obtained.

(2) Since the separation channel is incorporated in the substrate, an electrophoresis detection device which can be easily miniaturized as a whole is obtained.

According to the fourth aspect of the present invention, since a glass material is used for the substrate, the surface treatment is easy as in a commercially available glass capillary tube, and is optimal for a sample liquid to be detected. Measurement device can be obtained.

According to the fifth aspect of the present invention, when a polymer resin material is used for a substrate, a conductivity measuring device which can easily perform chemical modification suitable for separation can be obtained.

According to the sixth aspect of the present invention, (1) Since only the conductivity measurement electrode portion and a part of the liquid flow path need to be manufactured, an inexpensive conductivity measurement device can be obtained. (2) If the resolution is deteriorated, the capillary tube may be replaced, so that a conductivity measuring device that can reduce maintenance costs can be obtained.

Therefore, according to the present invention, it is possible to realize a conductivity measuring apparatus which can stably measure without a stagnation of a sample liquid or a buffer liquid, can improve accuracy, and can be downsized.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a main part configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a main part configuration of FIG. 1;

FIG. 3 is a side view of FIG. 2;

FIG. 4 is an explanatory view of a manufacturing process of FIG. 2;

FIG. 5 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 6 is a side sectional view of FIG. 5;

FIG. 7 is an explanatory diagram of a configuration of a conventional example generally used in the related art.

FIG. 8 is an explanatory view of a manufacturing process of FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Cover glass 3 Liquid flow path 4 Divide flow path 6 Buffer liquid tank 8 Buffer liquid tank electrode 10 Separation flow path 11 Sample liquid tank 12 Sample waste liquid tank 13 Sample liquid tank electrode 14 Sample waste liquid tank electrode 21 Branch Flow path 22 Branch flow path 23 Conductivity measuring electrode 24 Conductivity measuring electrode 25 First buffer waste liquid tank 26 Electrode for first buffer waste liquid tank 27 Second buffer waste liquid tank 28 Electrode for second buffer waste liquid tank 29 High voltage power supply for electrophoresis 31 High voltage power switch for electrophoresis 32 Power supply for sample injection 33 Power switch for sample injection 34 Conductivity detector 341 AC constant voltage power supply 342 Current detector 101 Glass substrate 102 Groove for electrode 103 Flow channel 104 Platinum electrode 105 Cover glass 106 Resin

Claims (6)

[Claims] 1. A conductivity measuring apparatus for measuring the conductivity of a measurement fluid, comprising: a liquid flow path provided on a substrate; at least two branch flow paths provided downstream of the liquid flow path; A conductivity measuring device, comprising: two conductivity measuring electrodes provided from a branch portion of a flow channel to the inside of the branch flow channel to measure the conductivity of the measurement fluid. 2. The conductivity measuring apparatus according to claim 1, further comprising: the liquid flow path, the branch flow path, and the two conductivity measurement electrodes formed by a semiconductor process. 3. The apparatus according to claim 1, further comprising a separation channel provided on said substrate and having one end connected to said liquid channel.
Or the conductivity measuring device according to claim 2. 4. The conductivity measuring apparatus according to claim 3, further comprising a substrate made of a glass material. 5. The conductivity measuring apparatus according to claim 3, further comprising a substrate made of a polymer resin material. 6. The conductivity measuring apparatus according to claim 1, further comprising a liquid flow path mainly constituted by a capillary tube.